In the following discussion certain articles and methods will be described for background and introductory purposes. Nothing contained herein is to be construed as an “admission” of prior art. Applicant expressly reserves the right to demonstrate, where appropriate, that the articles and methods referenced herein do not constitute prior art under the applicable statutory provisions.
According to the American Diabetes Association, diabetes is the fifth-deadliest disease in the United States and kills more than 213,000 people a year, the total economic cost of diabetes in 2002 was estimated at over $132 billion dollars, and the risk of developing type I juvenile diabetes is higher than virtually all other chronic childhood diseases.
In certain medical treatment and diagnostic procedures, it is necessary to transport body fluid from the patient to a remote location. For example, one such procedure is the testing of a sample of body fluid, such as blood, for the glucose concentration level contained therein. Such diagnostic procedures may be conducted clinically or by the patient utilizing a self-testing device or arrangement. There are numerous devices and systems designed to be utilized by the patient for obtaining a sample of blood, and testing the sample to determine the glucose content at a particular point in time. One such system generally includes at least three separate devices. The first device is utilized to draw a sample of blood from the patient by performing a lancing or similar skin piercing operation. Lancets are solid members which do not include a pathway for transporting the sample of blood. Since the lancets do not offer the ability to transport the sample, a separate member or component must be provided for this purpose. Typically, such systems include a separate test strip member which is manually brought into contact with the sample of blood produced by the lancing operation. The sample is then introduced onto the test strip, which includes a mechanism, such as a chemical reagent, for reacting with the blood sample and producing a readable signal. To this end, a separate meter or other reading device is also included in the system. The test strip is typically introduced into the meter, which then interacts with the test strip to produce the quantification of the glucose content contained in the sample of blood.
Such systems suffer from certain drawbacks. The manual operations of lancing, bringing the test strip into contact with the sample of blood thus produced, and the separate step of inserting the test strip into the meter may be difficult to perform for some patients. For instance, diabetics often times suffer from visual impairment as a result of their condition. Thus, it may be difficult for them to locate the sample of blood on the surface of the skin and bring the test strip into communication therewith. Similarly, it may be difficult to properly insert the test strip into the meter. In addition, there is a trend toward minimizing the size of the lancet used to perform the lancing operation in an effort to minimize the pain associated with this self testing procedure, thereby promoting more frequent testing. The use of a smaller gauge lancet also results in a smaller volume of body fluid, or blood, produced by the lancing operation. Such smaller samples of blood may be even more difficult to locate by the patient, and also may be more challenging to transport effectively.
Other systems for self-testing on the market attempt to integrate one or more above described lancing, transporting and quantification operations. One such system requires the user to load a lancet and a test strip into a device, which includes a meter. Once loaded the device is held against the skin and the test initiated by the user, which includes a lancing operation and subsequent transport of a sample of body fluid into the test strip. This arrangement still requires the manual step of loading a separate lancet and test strip correctly into the device, and orienting the device correctly at the surface of the skin in order to perform each test. This device also uses the lancet, which in and of itself does not provide a mechanism to transport the sample of blood. Thus, it is necessary to provide a separate mechanism, which enables transportation of the blood from the surface of the skin to the test strip. In this particular device, the transport function is performed by automatically moving the test strip, which includes capillary channels, into communication with the sample of blood at the surface of the skin. If the test strip is not loaded correctly, or the mechanisms for moving the test strip into position do not function correctly, the device will not function properly. Moreover, the user must purchase, store, handle and load the separate lancet and test strip components for each test. Thus, the successful performance for each test is again at least partially dependent upon the patient correctly associating the lancet and the test strip with the device for each and every test performed.
Yet another conventional self-testing system includes multiple disposable parts for lancing and analyte quantification. In this particular device, a test strip is provided which has an integrated blood transport member in the form of a capillary tube extending from a major planar surface thereof which must be brought into communication with the droplet of blood formed on the surface of the skin resulting from a lancing operation. In order to facilitate the transport function, the test strip is provided with a separate spreading layer sandwiched between the end of the capillary tube and a reagent membrane disposed on an opposing side thereof. The spreading layer facilitates transfer of the blood from the tube to the reagent layer. This system is designed such that a sample volume that completely fills the tube is required in order to obtain an accurate test result. Thus, approximately two micro liters of blood is typically required to be drawn from the patient such that the tube can be completely filled and transferred for further analysis. This requires creation of a wound in the skin large enough to express the necessary volume of blood, thus limiting lancet size reduction efforts. Also, the process of completely filling the tube is time consuming, and may require the user to apply significant efforts to manually express or milk a sufficient quantity of blood from the wound in order to fill the tube. This design also requires the blood to flow through the spreading layer prior to reaching the reagent layer. This two-layer structure is less than optimal from an assembly standpoint (i.e. requiring the assembly of multiple distinct layers), and since the volume of the capillary tube must be first transferred through the spreading layer, this may also have a tendency to slow down the testing procedure and reduce the volume of sample available for analysis. The spreading layer also retains a certain amount of the sample, thereby reducing the amount of the sample that is available for reaction with the reagent layer, and subsequent analysis thereof. Also, the spreading layer can alter certain characteristics of body fluids, such as whole blood. For instance, the spreading layer may alter the hematocrit contained in a sample of whole blood.
Thus, conventional body fluid transport systems for medical treatment and/or diagnostic procedures suffer certain drawbacks. Such drawbacks include transport operations that are reliant upon the dexterity and ability of the patient to accurately perform various manual procedures. The conventional devices and arrangements also are not fully integrated and require significant intervention on the part of the user in order to perform an accurate test.